626  Properties  and  Uses  of  Formaldehyde.  { X/embef %?.' 
rangement  for  effecting  this  consists  of  a  tinplate  tray  supported  on 
the  ring  of  a  retort  stand,  and  heated  by  a  spirit  lamp,  the  formal- 
dehyde solution  being  contained  in  a  glass  separator  held  in  an 
upper  ring  of  the  stand,  and,  by  regulation  of  the  stopcock,  allowed 
to  drop  slowly  on  to  the  heated  tray  beneath.  Careful  experiment 
has  shown  that  disinfection  with  formaldehyde  vapor  is  most  thorough 
and  effective,  the  vapor  diffusing  very  rapidly  and  penetrating  every- 
where, dust  on  the  walls,  in  the  air,  and  even  in  cupboards,  being 
almost  immediately  sterilized.  Owing  to  the  irritating  nature  of  the 
formaldehyde  fumes  on  the  mucous  membrane  and  air  passages,  it  is 
imperative  that,  after  disinfection  by  this  means,  currents  of  air 
should  be  allowed  to  pass  through  the  apartment  for  a  quarter  of  an 
hour  before  entering  it,  whilst  complete  removal  of  the  disinfectant 
should  be  ensured  by  free  ventilation  for  at  least  two  days. 
THE  COLORING  MATTER  OF  QUEBRACHO  COLORADO. 
An  investigation  of  the  coloring  matter  of  Quebracho  Colorado 
is  reported  by  Perkin  and  Gunnell  {Proc.  Chem.  Society,  1896,  p.  158). 
The  wood  of  Quebracho  Colorado  constitutes  the  tannin  matter 
"  quebracho,"  which  is  suitable  for  the  production  of  mor- 
occo leather,  and,  moreover,  in  conjunction  with  alum,  it  gives  the 
leather  a  bright  yellow  shade,  instead  of  the  darker  colors  prepared 
in  the  ordinary  way.  Jean  [Bull.  Soc.  Chim.,  33,  6)  found  it  to 
contain  a  tannin  differing  from  those  of  oak  bark  and  chestnut 
wood.  According  to  Arnaudon  {Watts'  Diet.  Chem.,  8,  1732),  it 
contains  a  yellow  coloring  matter. 
The  coloring  matter  C15H10O6  forms  glistening  yellow  needles, 
dyeing  shades  similar  to  those  of  quercetin,  and  yielding  compounds 
with  mineral  acids.  The  benzoyl  derivative  C15H606(C7H50)4  forms 
colorless  needles,  having  a  melting  point  of  i8o-i8i°,  and  the  acetyl 
derivative  C15H606(C2H30)4  is  in  the  form  of  colorless  needles,  melt- 
ing at  196-1980.  Fused  with  alkali  it  yields  protocatechuic  acid 
and  probably  resorcinol.  Its  dyeing  properties  are  found  to  be 
identical  with  those  of  fisetin,  C15H10O6,  the  coloring  matter  of  young 
fustic  (Rhus  cotinus),  and  there  can  be  little  doubt  that  it  is  fisetin. 
The  authors  also  report  the  presence  of  ellagic  and  gallic  acids, 
which  are  thought  to  be  formed  chiefly  during  the  isolation  of  the 
fisetin  from  the  quebracho. 
